Week Four Homework Exercise
Answer the following questions, covering material from Ch 8–10 of Methods in Behavioral Research:
1. What is a confounding variable and why do researchers try to eliminate confounding variables? Provide two examples of confounding variables.
2. What are the advantages and disadvantages of posttest only design and pretest-posttest design?
3. What is meant by sensitivity of a dependent variable?
4. What are the differences between an independent groups design and a repeated measures design?
5. How does an experimenter’s expectations and participant expectations affect outcomes?
6. Provide an example of a factorial design. What are the key features of a factorial design? What are the advantages of a factorial design?
7. Describe at least four different dependent variables.
8. What are some ways researchers can manipulate independent variables?
9. What is the difference between main effects and interactions?
10. How do moderator variables impact results? Provide an example.
11. A researcher is interested in studying the effects of story endings on preference ratings. He randomly assigns participants into two groups: predictable ending or surprise ending. He instructs them to read the story and provide preference ratings. The experimenter’s variation of story endings is a __________ (straightforward or staged) manipulation.
12. A researcher was interested in investigating the vocabulary skills of 6th graders in a program for gifted students. She gave a group of participants a test of vocabulary that was aimed at the 7th-grade level. She quickly discovered that there was limited variability in the scores because nearly all the students answered 90% or more of the questions correctly. This outcome is called a _______ effect.